Lose 10 Pounds in 10 Days!
Eat as Much as You Want -- and Still Lose Weight!
Drop One Dress Size a Day!
Rapid weight loss can be quick and easy -- if you believe the advertising claims.
Fad diets and weight loss supplements promise a slimmer body in no time. In the U.S. alone, consumers spend $33 billion each year on weight loss products.
Do any of these products really produce rapid weight loss? Are they safe? And what are the risks of such fast weight loss? WebMD took a look at some rapid weight loss claims, as well as the available evidence.
Rapid Weight Loss: What Is It?
So many marketers promise "fast weight loss" it's difficult to sort through them all.
Most rapid weight loss pitches fall into these categories:
Beyonce popularized the so-called "master cleanse" diet: water, lemon juice, maple syrup, and cayenne pepper. Variations of these diets have been around since at least the 1950s. They often also promise "detoxification" through colonics or enemas.
Diet Pills and Supplements
Dozens of diet supplements promise to speed weight loss. Generally, they claim either to block absorption of nutrients, increase metabolism, or burn fat.
Very Low-Calorie Diets (VLCDs)
One proven method of rapid weight loss is the medically supervised very low-calorie diet (VLCD). Most of what is known about rapid weight loss comes from studies of people on these diets.
Creams, Devices, and Magic Voodoo Spells
There seems to be no end to the dubious ideas promoted in the name of rapid weight loss. Most promise to replace diet or exercise.
Does Rapid Weight Loss Work?
The U.S. Food and Drug Administration (FDA) does regulate dietary supplements; however, it treats them like foods rather than medications.
The FDA also does not regulate claims made by over-the-counter weight loss products. Unlike drug manufacturers, the makers of supplements don’t have to show their products are safe or effective before selling them on the market. This means that dietary supplements do not need approval from FDA before they are marketed.
Aside from the very low-calorie diet and weight loss surgery, no other product, pill, or diet has been proven to work for fast weight loss. The prescription drug orlistat can help, but it works slowly and only with diet and exercise. Orlistat is marketed as Xenical and Alli. Labeling for orlistat notes that it can cause severe liver damage.
In any rapid weight loss program, what really burns fat is not a pill or type of food. It's the drastic reduction of calories, combined with exercise.
What Are the Risks of Rapid Weight Loss?
Rapid weight loss creates physical demands on the body. Possible serious risks include:
- Gallstones, which occur in 12% to 25% of people losing large amounts of weight over several months
- Dehydration, which can be avoided by drinking plenty of fluids
- Malnutrition, usually from not eating enough protein for weeks at a time
- Electrolyte imbalances, which rarely can be life threatening
Other side effects of rapid weight loss include:
- Menstrual irregularities
- Hair loss
- Muscle loss
The dangers of rapid weight loss increase with the time spent on the diet. Eating a no-protein diet is particularly risky.
Is Rapid Weight Loss Ever a Good Idea?
Rapid weight loss diets can have ill effects, but so does obesity. For this reason, very low-calorie diets (VLCDs) are considered a reasonable weight loss option for people with obesity (having a body mass index (BMI) greater than 30) needing rapid weight loss for a specific purpose such as weight loss surgery .
VLCDs are doctor-supervised diets lasting several weeks. The meals are nutritionally balanced, but expensive -- people can end up spending thousands of dollars over time. VLCDs safely produce a loss of 15% to 25% of body weight in 12 weeks. That's for those who finish the program: 25% to half of people don't complete the program. Weight returns when the diet is stopped and happens rapidly; some experts say its best to take a more sustainable approach to weight loss comparable to that of regular diets.
Most people seeking rapid weight loss, though, usually do it on their own. Frequently, it's to achieve a short-term goal, such as fitting into a dress, or looking good at the beach.
Starving yourself is certainly not a good idea. But if you're otherwise healthy, a brief period of extreme calorie restriction isn't likely to hurt you. You should tell your doctor what you're doing, and be sure to include protein in your diet (70 to 100 grams per day). Take a multivitamin, and eat potassium-rich foods (tomatoes, oranges, and bananas).
Also, remember that crash diets rarely help you achieve a sustained, healthy weight. Most people put the pounds right back on.
Reviewed by Brunilda Nazario, MD